#pragma section-numbers on
#pragma keywords Linux, kernel, operating system, changes, changelog, file system, Linus Torvalds, open source, device drivers
#pragma description Summary of the changes and new features merged in the Linux kernel during the 3.17 development cycle

Linux 3.17 [https://lkml.org/lkml/2014/10/5/126 has been released] on Sun, 5 Oct (this document was only finished on Sunday, 13 - sorry for the delay)

Summary: This release adds support for USB device sharing over IP, support for Xbox One controllers, support for Apple's thunderbolt, a new sealing API that restricts operations on shared memory file descriptors that allows easier shared memory programming for developers, support for page fault tracing in perf trace, support for only using signed kernels in kexec, a getrandom() syscall for more secure random number generation, and graphic "render nodes" are no longer experimental. There are also new drivers and many other small improvements.


[[TableOfContents()]]
= Prominent features =
== USB device sharing over IP ==
USB/IP is a project that provides a general USB device sharing system over IP network. To share USB devices between computers with their full functionality, USB/IP encapsulates "USB I/O messages" into TCP/IP payloads and transmits them between computer. Original USB device drivers and applications can be also used for remote USB devices without any modification of them. A computer can use remote USB devices as if they were directly attached.

This project has been for a while in the "staging" area, and it's now considered stable enough for prime consumption. Userspace tools can be found at [https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/tools/usb/usbip tools/usb/usbip]

Code: [http://git.kernel.org/linus/96c2737716d586a218bc795fcb79d2e2b6003081 commit], [http://git.kernel.org/linus/588b48caf65c4a92af567948ec0025065e749ddf commit]

Project: [http://usbip.sourceforge.net/ http://usbip.sourceforge.net]

== 'File sealing' eases handling of shared memory ==

When various processes communicate with each other via shared memory, they have to be careful and synchronize, because the shared memory can be modified by others at any time, or shrink and grow the buffer. This makes IPC via shared memory fragile, forces servers to do extra checks, encourages making local copies of shared memory and makes zero-copy operations impossible if the source of shared memory is not trusted.

This release includes the concept of "file sealing". Files from shmfs can be "sealed" through [http://linux.die.net/man/2/fcntl fcntl(2)] different flags that restrict determinate behaviours: shrinking the file, growing, writing to it or setting new seals.

Sealing allows sharing shmfs files without any trust-relationship. This is enforced by rejecting seal modifications if you don't own an exclusive reference to the given file. So if a process owns a file-descriptor, it can be sure that no-one besides him can modify the seals on the given file. This allows mapping shared files from untrusted parties without the fear of the file getting truncated or modified by an attacker.

This has some useful uses. For example, a graphic server (e.g. Wayland) may want to reject any file descriptors that don't have the SEAL_SHRINK seal set. That way, any memory-mappings are guaranteed to stay accessible (while at the same time allowing to grow the buffer). Another example would be a general purpose IPC mechanism such as D-Bus. With sealing, zero-copy can be easily done by sharing a file-descriptor that has SEAL_SHRINK | SEAL_GROW | SEAL_WRITE seals set. This way, the source can store sensible data in the file, seal the file and then pass it to the destination. The destination verifies these seals are set and then can parse the message in-line, or even do safe multicasts of the message and allow all receivers parse the same zero-copy file without affecting each other.

Recommended LWN article: [http://lwn.net/Articles/593918/ Sealed files]

Recommended blog article: [https://dvdhrm.wordpress.com/2014/06/10/memfd_create2/ memfd_create(2)]

Code and preliminary API documentation: [http://git.kernel.org/linus/40e041a2c858b3caefc757e26cb85bfceae5062b commit], [http://git.kernel.org/linus/9183df25fe7b194563db3fec6dc3202a5855839c commit]

== Graphic "render nodes" feature enabled by default ==
"Render nodes" is a feature [http://kernelnewbies.org/Linux_3.12#head-276162293c22a1526d6a5162f3cb7d802ea5fc43 merged in Linux 3.12]. It allows to create different device nodes for the GPU and the display, thus allowing applications to use the GPU for off-screen rendering by talking directly to the DRM device node.

This feature had been considered experimental for a while and could only be enabled with the "drm.rnodes=1" module parameter. In this release, render nodes have been enabled by default.

For more details about render nodes, see [https://dvdhrm.wordpress.com/2013/09/01/splitting-drm-and-kms-device-nodes/ this blog]

Code: [http://git.kernel.org/linus/6d6dfcfb883818b40b58bac61cc72cab428a7a03 commit]

== Improved power management features enabled for more Radeon GPUs ==
Dynamic power management (dpm) has been re-enabled by default on Cayman and BTC devices.

Also, a new module parameter (radeon.bapm=1) has been added to enable bidirectional application power management (bapm) on APUs where it's disabled by default due to stability issues.

Code: [http://git.kernel.org/linus/c08abf11900e19b14dd3a0cc3d105bd74519cd18 commit], [http://git.kernel.org/linus/8f500af4efe347d1a8ac674d115220e8caa84559 commit], [http://git.kernel.org/linus/6e909f74db2aa9c5b5606b81efcbe18f2749b008 commit]


== Thunderbolt support ==

[http://en.wikipedia.org/wiki/Thunderbolt_%28interface%29 Thunderbolt] is a hardware interface that combines PCI Express and Displayport into one serial signal alongside a DC connection for electric power, transmitted over one cable. Up to six peripherals may be supported by one connector through various topologies. Co-developed by Intel and Apple, it's mostly used in Apple devices.

Code: [http://git.kernel.org/linus/16603153666d22df544ae9f9b3764fd18da28eeb commit]

== Support for Xbox One controllers ==
This release adds support for Xbox One controllers.

Code: [http://git.kernel.org/linus/1a48ff81b3912be5fadae3fafde6c2f632246a4c (commit)]

== More secure generation of random numbers with the getrandom() syscall ==
Linux systems usually get their random numbers from /dev/[u]random. This interface, however, is vulnerable to file descriptor exhaustion attacks, where the attacker consumes all available file descriptors, and is inconvenient for containers. The getrandom(2) syscall, analogous to OpenBSD's getentropy(2), solves that problems.

Recommended LWN article: [http://lwn.net/Articles/606141/ A system call for random numbers: getrandom()]

Code: [http://git.kernel.org/linus/c6e9d6f38894798696f23c8084ca7edbf16ee895 commit]

== Support for page fault tracing in perf trace ==

This release adds page fault tracing support to 'perf trace'. Using -F/--pf option user can specify whether he wants minor, major or all pagefault events to be traced. Output example:

{{{1756272.905 ( 0.000 ms): curl/5937 majfault [0x7fa7261978b6] => /usr/lib/x86_64-linux-gnu/libkrb5.so.26.0.0@0x85288 (d.)
1862866.036 ( 0.000 ms): wget/8460 majfault [__clear_user+0x3f] => 0x659cb4 (?k)}}}

Code: [http://git.kernel.org/linus/598d02c5a07b60e5c824184cdaf697b70f3c452a commit], [http://git.kernel.org/linus/1e28fe0a4ff8680d5a0fb84995fd2444dac19cc4 commit], [http://git.kernel.org/linus/a2ea67d7b5618c868c1fe15a50af71b858d36887 commit]

== perf timechart adds I/O mode ==

Currently, perf timechart records only scheduler and CPU events (task switches, running times, CPU power states, etc); this release adds I/O mode which makes it possible to record IO (disk, network) activity. In this mode perf timechart will generate SVG with I/O charts (writes, reads, tx, rx, polls).

Code: [https://git.kernel.org/linus/b97b59b93d10a54022afb06d5725d7aa55d98dd7 commit], [https://git.kernel.org/linus/d243144af0b52fc5164a0823194f29a5979e236c commit]


== Signed kexec kernels ==

Kexec is a Linux feature that allows to boot a Linux kernel from an existing Linux kernel. It is used for faster rebooting or even for automatically booting a new kernel after a crash. However, UEFI "secure boot" systems are not supposed to allow to boot unsigned operating systems. Kexec allows to bypass the UEFI secure boot by kexec'ing into a unsigned kernel. To solve this problem, this release incorporates support for only allowing to kexec kernels that are signed.

Recommended LWN article: [http://lwn.net/Articles/603116/ Reworking kexec for signatures]

Code: [http://git.kernel.org/linus/f0895685c7fd8c938c91a9d8a6f7c11f22df58d2 commit], [http://git.kernel.org/linus/cb1052581e2bddd6096544f3f944f4e7fdad4c7f commit], [http://git.kernel.org/linus/dd5f726076cc7639d9713b334c8c133f77c6757a commit], [http://git.kernel.org/linus/8fc5b4d4121c95482b2583a07863c6b0aba2d9e1 commit], [http://git.kernel.org/linus/daeba0641a707626f3674db71016f333edf64395 commit], [http://git.kernel.org/linus/6a2c20e7d8900ed273dc34a9af9bf02fc478e427 commit], [http://git.kernel.org/linus/8e7d838103feac320baf9e68d73f954840ac1eea commit]



= Drivers and architectures =
All the driver and architecture-specific changes can be found in the [http://kernelnewbies.org/Linux_3.17-DriversArch Linux_3.17-DriversArch page]

= Core =
 * A resizable, Scalable, Concurrent Hash Table [http://git.kernel.org/linus/7e1e77636e36075ebf118298855268468f1028e8 commit]
 * firmware loader: allow disabling of udev as firmware loader [https://git.kernel.org/linus/5a1379e8748a5cfa3eb068f812d61bde849ef76c commit]
 * Add a option to enable dwarf4 debug info format [https://git.kernel.org/linus/bfaf2dd3509bc73bf4a4cea0e72472755ed860e2 commit]
 * Support the "[http://gcc.gnu.org/wiki/DebugFission split debug info]" debug info model present in gcc 4.7+ and newer binutils. It avoids having to copy it around multiple times, from the object files to the final executable, lowers the disk space and defaults to compressed debug data [https://git.kernel.org/linus/866ced950bcd54820c3e571229356adc2b2dd72e commit]
 * Support initramfs and initrd bigger than 2 GiB [https://git.kernel.org/linus/d97b07c54f34e88352ebe676beb798c8f59ac588 commit], [https://git.kernel.org/linus/38747439914c468ecba70b492b54dc4ef0b50453 commit]
 * sysfs: disallow world-writable files. [http://git.kernel.org/linus/37549e94c77a94a9c32b5ae3313a3801cb66adf9 commit]
 * rcu: Remove CONFIG_PROVE_RCU_DELAY [http://git.kernel.org/linus/11992c703a1c7d95f5d8759498d7617d4a504819 commit]

= Memory management =
 * dma-buf: add poll support [https://git.kernel.org/linus/9b495a5887994a6d74d5c261d012083a92b94738 commit]
 * dma-buf: A new "fence" mechanism allows to do cross-device synchronization of DMA buffers. Fences are attached to a buffer which is being filled or consumed by hardware, to allow userspace to pass the buffer without waiting to another device. For example, userspace can call page_flip ioctl to display the next frame of graphics after kicking the GPU but while the GPU is still rendering.  The display device sharing the buffer with the GPU would attach a callback to get notified when the GPU's rendering-complete IRQ fires, to update the scan-out address of the display, without having to wake up userspace  [https://git.kernel.org/linus/e941759c74a44d6ac2eed21bb0a38b21fe4559e2 commit], [http://git.kernel.org/linus/606b23ad609c71cfb37eeb972ea4c901034edd3c commit]


 * iommu: Add sysfs support [https://git.kernel.org/linus/c61959ecbbc6bf9034e65c8e8ef03fa9d1066f05 commit], [https://git.kernel.org/linus/066f2e98d8c7f043747fb08ebaa66bad723b1121 commit]
 * Export NR_SHMEM via sysinfo(2) / si_meminfo() interfaces [http://git.kernel.org/linus/cc7452b6dca384400960d40090a98d0eb920ab22 commit]

= Block layer =
 * brd: add module option to enable RAM disk visibility in /proc/partitions [https://git.kernel.org/linus/aeac31819475ad0980cb3a13d5599f5a1127e83d commit]
 * drbd: New net configuration option socket-check-timeout [https://git.kernel.org/linus/5d0b17f1a29e8189d04aef447a3a53cfd05529b2 commit]

= Power management =
  * scripts/analyze_suspend.py: update to v3.0, which includes back-2-back suspend testing, device filters to reduce the html size, the inclusion of device_prepare and device_complete callbacks, a USB topography list, and the ability to control USB device autosuspend [http://git.kernel.org/linus/b8432c6fc12bdf4a6921e1640d3ead23fcd04c10 commit]


= File systems =
 * Btrfs
  * Adjust statfs() space utilization calculations according to RAID profiles [https://git.kernel.org/linus/ba7b6e62f420f5a8832bc161ab0c7ba767f65b3d commit]
 * XFS
  * Add a sysfs /sys/fs/xfs/ directory with various files providing information about XFS filesystems [http://git.kernel.org/linus/3d8712265c26546823b38eb97487262500ff13db commit], [http://git.kernel.org/linus/a31b1d3d89e40f585a1c6745b066774ee3263eb2 commit], [http://git.kernel.org/linus/80d6d69821a27c3cd4687c2eefe409cbd1b7f458 commit], [http://git.kernel.org/linus/baff4e44b92aad363dcce176b907a369ee8b348e commit], [http://git.kernel.org/linus/a087481811bed920eb5eedbb5574b915881adbea commit]
  * Create libxfs infrastructure, libxfs will be used by userspace tools [http://git.kernel.org/linus/69116a1317ce3d2292e062bfb1a22757b95dcd06 commit]

 * SMB
  * Add sparse file support [https://git.kernel.org/linus/3d1a3745d8ca7ccdf00905b01fd5ab42ff523a94 commit]
  * Enable fallocate punch hole ("fallocate -p") [https://git.kernel.org/linus/31742c5a331766bc7df6b0d525df00c6cd20d5a6 commit]
  * Enable fallocate -z support [https://git.kernel.org/linus/30175628bf7f521e9ee31ac98fa6d6fe7441a556 commit]

 * f2fs
  * Add nobarrier mount option [https://git.kernel.org/linus/0f7b2abd188089a44f60e2bf8521d1363ada9e12 commit]
  * Support cross-rename rename2() syscall [https://git.kernel.org/linus/32f9bc25cbda00410e2379c58ae027e88bf24770 commit]
  * Support O_TMPFILE [https://git.kernel.org/linus/50732df02eefb39ab414ef655979c2c9b64ad21c commit]

 * nilfs2
  * Add /sys/fs/nilfs2 directory with several files that provide information about the filesystem [https://git.kernel.org/linus/da7141fb78db915680616e15677539fc8140cf53 commit], [https://git.kernel.org/linus/02a0ba1c60c2ad532322089a60256c8b0f46678c commit], [https://git.kernel.org/linus/a2ecb791a9d6e71a2d37d66034475a92ebc7e02c commit], [https://git.kernel.org/linus/a5a7332a291b55beb0863b119816d12ffc04dfb0 commit], [https://git.kernel.org/linus/abc968dbf291955ac750ecf59e3baf2b529a8257 commit], [https://git.kernel.org/linus/ef43d5cd84b7d2ea09846de34e14be7d74be3e6f commit],  [https://git.kernel.org/linus/caa05d49dfd7fe04820ba8b7e424343d5426a7f3 commit], [https://git.kernel.org/linus/aebe17f6844488ff0b824fbac28d9f342f7b078e commit]

 * NFS
  * Add a new /proc/fs/nfsd/max_connections file [https://git.kernel.org/linus/5b8db00bae39e5ecd9bafb05478cca5b42564ab1 commit]

= Networking =
 * ipv6: Implement automatic generation of flow labels for IPv6 packets on transmit [https://git.kernel.org/linus/cb1ce2ef387b01686469487edd45994872d52d73 commit]
 * openvswitch: Enable tunnel GSO for Open vSwitch bridge. [http://git.kernel.org/linus/f6eec614d2252a99b861e288b6301599d2d58da4 commit]

 * timestamp: ACK timestamp for bytestreams [http://git.kernel.org/linus/e1c8a607b28190cd09a271508aa3025d3c2f312e commit]
 * timestamp: SCHED timestamp on entering packet scheduler [http://git.kernel.org/linus/e7fd2885385157d46c85f282fc6d7d297db43e1f commit]
 * timestamping: TCP timestamping [http://git.kernel.org/linus/4ed2d765dfaccff5ebdac68e2064b59125033a3b commit]
 * Remove deprecated syststamp timestamp [http://git.kernel.org/linus/4d276eb6a478307a28ae843836c455bf04b37a3c commit]
 * bridge: netlink dump interface at par with brctl [http://git.kernel.org/linus/5e6d243587990a588143b9da3974833649595587 commit]
 * Wireless
  * Add support for Rx reordering offloading [http://git.kernel.org/linus/08cf42e843f9a7e253502011c81677f61f7e5c42 commit]
  * Remove PID controller based rate control algorithm [http://git.kernel.org/linus/20edb50e593dca7522b4f3a95b801dbf99f24c52 commit]
 
 * Bluetooth
  * Add support for background LE scanning [http://git.kernel.org/linus/0d2bf13462732d3b2e11d8efb0545c1ed272298b commit]
  * Add support for changing the public device address [http://git.kernel.org/linus/9713c17b086c1ebfe34ea4d34147a778276e2dab commit]
  * Add support for several new commands [http://git.kernel.org/linus/2faade53e65f276cf1c30a885fb64808a083714e commit][http://git.kernel.org/linus/958684263d3efbc721fb2b86f94876893eb638d2 commit], [http://git.kernel.org/linus/9fc3bfb681bdf59999f56072fff4632a5abea897 commit], [http://git.kernel.org/linus/73d1df2a7a1036a1f000e5f0ece6ade3e082b854 commit], [http://git.kernel.org/linus/dbece37a3233933ec89f77f04049e13ad9b29634 commit], 
  * Add support for some new events [http://git.kernel.org/linus/f4537c04d387eda86ed89e0eafe0352f7fa0c9d0 commit], [http://git.kernel.org/linus/c70a7e4cc8d22cb1ce684637ef8a4bb3a80d15b7 commit], [http://git.kernel.org/linus/0602a8adc3ce3f592d03df426c92d1f36229403c commit], [http://git.kernel.org/linus/edd3896bc41059fc064c4ec76da004a57203d88e commit]


 * netfilter/nftables
  * Add generic ARP packet logger [http://git.kernel.org/linus/35b9395104d51f4b85847fa72a1bf4136d36c56e commit]
  * bridge: add generic packet logger [http://git.kernel.org/linus/960649d1923c31a7f771162fa0eef00210044262 commit]
  * bridge: add reject support [http://git.kernel.org/linus/85f5b3086a04c459f9147859fcbf7bdc7578c378 commit]
  * kill ulog targets (deprecated by the NFLOG target) [http://git.kernel.org/linus/7200135bc1e61f1437dc326ae2ef2f310c50b4eb commit]
  * nft_log: complete logging support [http://git.kernel.org/linus/09d27b88f15f08fcfbaf57d9b0b4489816264815 commit]



 * SCTP
  * Deprecate rfc6458, 5.3.2. SCTP_SNDRCV support [https://git.kernel.org/linus/bbbea41d5e53335fd81e89c728f71b14386f336e commit]
  * Implement rfc6458, 5.3.4. SCTP_SNDINFO cmsg support [https://git.kernel.org/linus/63b949382c5f263746b1c177f6ff84de2201ae9d commit]
  * Implement rfc6458, 5.3.5. SCTP_RCVINFO cmsg support [https://git.kernel.org/linus/0d3a421d284812d07970b4ccee74d4fa38737e4d commit]
  * Implement rfc6458, 5.3.6. SCTP_NXTINFO cmsg support [https://git.kernel.org/linus/2347c80ff127b94ddaa675e2b78ab4cef46dc905 commit]
  * Implement rfc6458, 8.1.31. SCTP_DEFAULT_SNDINFO support [https://git.kernel.org/linus/6b3fd5f3a2bbc8464a8e0bf134a183b8fa026439 commit]

= Virtualization =
 * virtio-blk: support multiple virtual queues that can get assigned to host's hardware queues [https://git.kernel.org/linus/6a27b656fc0210e976db362e1368c56db05c8f08 commit]
 * virtio-net: rx busy polling support, 1 byte netperf tcp_rr shows 127% improvement [http://git.kernel.org/linus/91815639d8804d1eee7ce2e1f7f60b36771db2c9 commit]
 * vfio: EEH support for VFIO PCI device [https://git.kernel.org/linus/1b69be5e8afc634f39ad695a6ab6aad0cf0975c7 commit]
 * hyperv: Add netpoll support [https://git.kernel.org/linus/316158feff0078b266d6e423adb016d12eb96a5a commit]
 * xen: EFI under Xen dom0 support [http://git.kernel.org/linus/bf1e3ae468aca7ce34110a59ed5d1b877890014b commit], [http://git.kernel.org/linus/be81c8a1da24288b0231be50130a64f5cdffdcd4 commit]


= Tracing/perf =
 * perf timechart: add IO mode [https://git.kernel.org/linus/b97b59b93d10a54022afb06d5725d7aa55d98dd7 commit], [https://git.kernel.org/linus/d243144af0b52fc5164a0823194f29a5979e236c commit]
 * perf trace: Add support for pagefault tracing [https://git.kernel.org/linus/1e28fe0a4ff8680d5a0fb84995fd2444dac19cc4 commit], [https://git.kernel.org/linus/598d02c5a07b60e5c824184cdaf697b70f3c452a commit], add pagefault statistics [https://git.kernel.org/linus/a2ea67d7b5618c868c1fe15a50af71b858d36887 commit]
 * perf trace: Add possibility to switch off syscall events [https://git.kernel.org/linus/e281a9606d7073c517f2571e83faaff029ddc1cf commit]
 * perf bench: Add --repeat option [https://git.kernel.org/linus/b6f0629a94f7ed6089560be7f0561be19f934fc4 commit]
 * perf hists browser: Display columns header text on 'H' press [https://git.kernel.org/linus/81a888fea2cfd727052926e95510c11981d9b1c2 commit], [https://git.kernel.org/linus/c83023676dc34f1b4422b842e1e2dc5c21bfc4dc commit]
 * perf inject: Add --kallsyms parameter [https://git.kernel.org/linus/a7a2b8b4ce9e0bfd085c5797d535487594a71882 commit]
 * perf kvm: Add stat support on s390 [https://git.kernel.org/linus/3be8e2a0a53c3179a44a933614f6a893da0b5c19 commit]
 * perf tools: Add --debug optionto set debug variable [https://git.kernel.org/linus/bbb2cea7e8dd496b41558df1a0ec9205497b7ebf commit]
 * tracing: Add ftrace_graph_notrace boot parameter for specifying notrace filter for function graph tracer at boot time [http://git.kernel.org/linus/0d7d9a16ce112687487fadb2b490519b45f6c70e commit]

= Security =
 * Allow seccomp to set a filter across all threads ([http://lwn.net/Articles/600250/ Recommended LWN Article]) [http://git.kernel.org/linus/3ba2530cc06eb4aee4f1f754f43d781e8a12ee09 commit], add "seccomp" syscall [http://git.kernel.org/linus/48dc92b9fc3926844257316e75ba11eb5c742b2c commit]
 * seccomp: implement SECCOMP_FILTER_FLAG_TSYNC [http://git.kernel.org/linus/c2e1f2e30daa551db3c670c0ccfeab20a540b9e1 commit]
 * selinux:  Report permissive mode in avc: denied messages. [http://git.kernel.org/linus/626b9740fa73cad043e136bfb3b6fca68a4f8a7c commit]


= Crypto =
 * drbg: NIST SP800-90A compliant Deterministic Random Bit Generator [http://git.kernel.org/linus/541af946fe1360ec1b45730964e87d7f93c50781 commit], [http://git.kernel.org/linus/419090c6c6862abb54b7c77efc3c00ed35909d73 commit]
 * Parser for a PKCS#7 signed-data message as described in part of RFC 2315 [https://git.kernel.org/linus/2e3fadbf730fd0d13c891d5e555af3e7f39ca3f4 commit]
 * pefile: Support for PE file signature verification [http://git.kernel.org/linus/26d1164be37f1145a96af15f294122876d8e5c77 commit]


= Other news sites that track the changes of this release =
 * LWN Merge window, [http://lwn.net/Articles/607627/ part 1], [http://lwn.net/Articles/608434/ part 2] and [http://lwn.net/Articles/608748/ part 3]
 * Phoronix [http://www.phoronix.com/scan.php?page=news_item&px=MTc5ODM The Top Features Of The Linux 3.17 Kernel]